1. Field of the Invention
The present invention relates to an ion generator of an ion implanter, and more particularly, to an ion generator of an ion implanter which can generate an electric field in an arc chamber of the ion generator, thereby improving an ion extraction rate from the arc chamber.
2. Description of the Related Art
In a semiconductor manufacturing process, an ion implanter is utilized in an ion implantation process so that a wafer has an electrical property by implanting impurities in the wafer. Namely, an ion implanter is one of a number of semiconductor manufacturing apparatuses (equipment) for an ion implantation process. Also, the ion implantation process is a basic process for implanting impurities in a wafer. A principal of an ion implanting technology is to physically fill in a wafer by applying a high energy beam of ions to the wafer. In this instance, a method of implanting ions of boron (B), phosphorus (P), arsenic (As), antimony (Sb), etc., which is group 3 or group 5 of the periodic table, in silicon, which is group 4 of the periodic table, is generally utilized.
FIG. 1 is a diagram illustrating a configuration of an ion implanter according to the conventional art (prior art).
As illustrated in FIG. 1, the ion implanter 100 may include an ion generator 110, an acceleration electrode 120, an electromagnet 130, and an ion beam shape correction electrode 140. In this instance, the ion generator 110 generates predetermined ions and extracts the generated ions via the acceleration electrode 120 accelerating the ions. Also, the electromagnet 130 selects only necessary ions from the accelerated ions and transmits the selected ions to the ion beam shape correction electrode 140. The ion beam shape correction electrode 140 corrects an ion beam shape of the selected ions and implants the same in a wafer 150, which may be on a base 160. As the ions are implanted in the wafer 150, the wafer 150 gains an electrical property.
FIG. 2 is a diagram illustrating a configuration of an ion generator of an ion implanter according to a conventional art.
As illustrated in FIG. 2, the ion generator may include an arc chamber 210 and an extraction electrode 220. The arc chamber 210 may include a filament 211, a gas discharge device 212, a slit 213 and a repeller 215.
When the filament 211 is heated to a predetermined temperature, the filament 211 generates electrons. When a voltage Vf is supplied to the arc chamber 210 and the filament 211, the generated electrons are then accelerated to obtain an energy necessary for generating ions. In this instance, the generated electrons may disappear into a wall surface of the arc-chamber 210 because of an electrical property generated inside of the arc chamber 210. Also, the electrons accelerated towards the repeller 215 may be re-accelerated to the inside of the arc chamber 210 by a repulsion force. In this instance, the repulsion force is generated by the repeller 215 which is charged to be negative.
Also, the gas discharge device 212 injects a predetermined neutral gas into the arc chamber 210. The injected neutral gas is bombarded with the electrons, thereby generating ions. When the generated ions exist in an extractable region 214, the ions are extracted from the arc chamber 210 to the extraction electrode 220 via the slit 213. Namely, since a voltage Ve is supplied to the extraction electrode 220, an electric field is generated between the arc chamber 210 and the extraction electrode 220, and the ions may be extracted to the extraction electrode 220 via the slit 213 by the electric field.
In this instance, in the case of ions not existing in the extractable region 214, the ions are not extracted to the extraction electrode 220 and linger in the arc chamber 210. The ions residing in the arc chamber 210 may bombard the filament 211 and the repeller 215, thereby causing damage thereto. Also, as the residing ions are increased, an electric field distribution in the arc chamber 210 is temporally changed. Accordingly, a possibility that an arc occurs around the filament 211 and the repeller 215 is increased.
Also, in an ion supplying apparatus according to the conventional art, ions to be generated may not exist in the extractable region 214. Accordingly, only a small number of ions is extracted from the arc chamber 210 and a number of residing ions in the arc chamber 210 increases. Also, since it is highly possible that the above-described situation may repeatedly occur, an effectiveness of this ion implantation process is deteriorated.
Accordingly, an ion generator which can reduce lingering ions in the arc chamber 210 by effectively extracting ions from the arc chamber 210 to the extraction electrode 220 via the slit 213 is required.